[ci] Print docker invocation; whitespace:

dedent does not work because {log} is not indented.

.github/workflows/root-ci-config/build_root.py

@@ -127,7 +127,7 @@ def main():
 
     if testing:
         extra_ctest_flags = ""
-        
+
         if WINDOWS:
             extra_ctest_flags += "--repeat until-pass:3 "
             extra_ctest_flags += "--build-config " + args.buildtype
@@ -165,7 +165,7 @@ def cleanup_previous_build(shell_log):
 
     if result != 0:
         die(result, "Failed to clean up previous artifacts", shell_log)
-    
+
     return shell_log
 
 
@@ -191,7 +191,7 @@ def git_pull(repository:str, branch: str, shell_log: str):
 
     if returncode != 0:
         die(returncode, f"Failed to pull {branch}", shell_log)
-    
+
     return shell_log
 
 
@@ -212,7 +212,7 @@ def download_artifacts(obj_prefix: str, shell_log: str):
         shutil.rmtree(f'{WORKDIR}/src', ignore_errors=True)
         shutil.rmtree(f'{WORKDIR}/build', ignore_errors=True)
         raise err
-    
+
     return shell_log
 
 
@@ -222,10 +222,10 @@ def run_ctest(shell_log: str, extra_ctest_flags: str) -> str:
         cd '{WORKDIR}/build'
         ctest --parallel {os.cpu_count()} --output-junit TestResults.xml {extra_ctest_flags}
     """, shell_log)
-    
+
     if result != 0:
         print_warning("Some tests failed")
-    
+
     return shell_log
 
 
@@ -271,25 +271,25 @@ def build(options, buildtype, shell_log):
 
     if result != 0:
         die(result, "Failed to build", shell_log)
-    
+
     return shell_log
 
 
 @github_log_group("Rebase")
 def rebase(base_ref, head_ref, shell_log) -> str:
-    # This mental gymnastics is neccessary because the the CMake build fetches 
+    # This mental gymnastics is neccessary because the the CMake build fetches
     # roottest based on the current branch name of ROOT
     #
     # rebase fails unless user.email and user.name is set
     result, shell_log = subprocess_with_log(f"""
         cd '{WORKDIR}/src'
-        
+
         git config user.email "rootci@root.cern"
         git config user.name 'ROOT Continous Integration'
-        
+
         git fetch origin {head_ref}:__tmp
         git checkout __tmp
-        
+
         git rebase {base_ref}
         git checkout {base_ref}
         git reset --hard __tmp

.github/workflows/root-ci-config/build_utils.py

@@ -26,7 +26,7 @@ def github_log_group(title: str):
             except Exception as e:
                 print("::endgroup::")
                 raise e
-            
+
             print("::endgroup::")
 
             return result
@@ -82,13 +82,17 @@ def die(code: int = 1, msg: str = "", log: str = "") -> None:
 
 def print_shell_log(log: str) -> None:
     if log != "":
-        shell_log = textwrap.dedent(f"""\
-            ######################################
-            #    To replicate build locally     #
-            ######################################
-            
-            {log}
-        """)
+        shell_log = f"""\
+######################################
+#    To replicate build locally     #
+######################################
+
+For Linux, grab the image:
+$ docker run --rm -it registry.cern.ch/root-ci/<image>:buildready
+Then:
+
+{log}
+"""
 
         print(shell_log)
 
@@ -183,7 +187,7 @@ def download_latest(url: str, prefix: str, destination: str, shell_log: str) ->
     with get(f"{url}/?prefix={prefix}&format=json", timeout=20) as r:
         if r.status_code == HTTPStatus.NO_CONTENT or r.content == b'[]':
             raise Exception(f"No object found with prefix: {prefix}")
-            
+
         result = json.loads(r.content)
         artifacts = [x['name'] for x in result if 'content_type' in x]